The Tanat Valley Light Railway (TVLR) was a 15-mile (24 km) long standard gauge light railway. It ran westwards from Llanyblodwel in Shropshire, about 5 miles or 8 km south-west of Oswestry. It crossed the Wales–England border and continued up the Tanat valley, terminating at Llangynog in Powys. It opened in 1904, providing access to a fairly remote area, and transport facilities for slate production and agriculture.
Its promoters were unable to raise the capital to construct the line, but a number of government grants and considerable generosity by the Cambrian Railways company enabled the building of the line. The company was always in debt and in 1921 was obliged to sell the line to the Cambrian Railways.
Rural passenger use collapsed and the railway closed to passengers in 1951, and completely in 1964.
A new Tanat Valley Light Railway Company was established, and in 2009 opened a heritage railway centre at Nantmawr, close to the earlier Tanat Valley line.
There were many populous villages in the area between the Great Western Railway route through Llangollen, to the north and the Cambrian Railways line through Welshpool to the south. The Berwyn and Aran mountains (with steep gradients and sparse population) together formed a barrier for a through railway line westwards towards the coast. Slate quarrying and agriculture were the area's dominant industries, and both suffered in the mid 19th century from transport difficulties.
Several schemes were put forward over the years, but they failed due to lack of interest from subscribers. One ambitious scheme was to extend the West Midland Railway through the region, passing through Montgomery and Bala, penetrating the Berwyns by a long tunnel. If this scheme had been successful, it would perhaps have given the Great Western Railway a trunk line to Holyhead; as it was, the Chester and Holyhead Railway was adopted instead.